1. Field of the Invention
The present invention relates to a method of manufacturing an optical waveguide device which provides an optical waveguide for widespread use in optical communications, optical information processing and other general optics together with a board.
2. Description of the Related Art
In general, an optical waveguide includes cores serving as a passageway for light and formed in a predetermined pattern on a board either directly or with an under cladding layer therebetween, and an over cladding layer formed to cover the cores. The optical waveguide is incorporated in an optical device such as an optical waveguide device, an optical integrated circuit, an optical wiring board and the like, and is used as a medium for propagating light from an optical element, an optical fiber and the like. In the use of the optical waveguide, the optical element, the optical fiber or the like is typically joined to a light receiving end surface and a light emitting end surface of the optical waveguide. Thus, the light receiving end surface and the light emitting end surface of the optical waveguide are required to be smooth for the purpose of reducing light propagation losses (coupling losses) due to the joining.
There has been proposed a method of manufacturing the above-mentioned optical waveguide as described below. This method is disclosed in Japanese Patent Application Laid-Open No. 2006-23375. First, an under cladding layer is formed over substantially the entire surface of a sizeable board, and a plurality of cores are formed in a plurality of regions, respectively, of the under cladding layer. Next, an over cladding layer is formed over the entire upper surface of the under cladding layer so as to cover the plurality of cores. This provides a film element composed of the under cladding layer, the cores and the over cladding layer on the board. The regions in which the cores are formed are future optical waveguide portions in which the optical waveguide is to be formed. Next, the film element is cut or diced together with the board into a plurality of pieces corresponding to the respective future optical waveguide portions one by one with a blade (a rotary blade). This provides a plurality of optical waveguide devices separated from each other and each including the optical waveguide formed on the diced board.
The above-mentioned dicing achieves a smooth light receiving end surface and a smooth light emitting end surface because the dicing is performed while the blade grinds the cut surfaces. Thus, joining the smooth light receiving end surface and the smooth light emitting end surface to the optical element, the optical fiber or the like reduces the coupling losses at the joints to achieve efficient light propagation using the optical waveguide as a medium.
However, the dicing which is cutting using the rotary blade is required to be performed for each cut surface. Additionally, the optical waveguide is often complicated in overall shape depending on the applications thereof. For these reasons, the process of dicing the film element formed with the plurality of future optical waveguide portions into the plurality of pieces corresponding to the respective future optical waveguide portions one by one results in low productivity.
To solve the problem, the present inventor has studied a cutting method by die-cutting using a cutting die. This has improved the productivity, but has provided less smooth cut surfaces than those obtained by dicing to result in accordingly increased coupling losses at the cut surfaces.